In a hybrid type vehicle drive apparatus equipped with an internal combustion engine and a rotating machine (such as motor, generator, motor generator), there is provided a transmission case accommodating therein a transmission mechanism, a power splitting mechanism, a differential mechanism, and other operating mechanism in addition to the rotating machine in a highly dense state, so that these mechanisms are required to be sufficiently lubricated and cooled, while the rotating machine is also necessary to be sufficiently cooled. For a vehicle drive apparatus having a plurality of rotating machines such as motor generators and the like (hereinafter, simply referred to as “motor generator”), it is required to properly cool the motor generators to prevent the motor generators from being lowered in efficiency when each of the motor generators is operated with a maximum heat generation amount being produced. For this reason, it is essential to provide a cooling structure for cooling the motor generators and their peripheral portions collectively constituting a heat-generating portion.
As a conventional vehicle drive apparatus provided with this kind of motor cooling structure, there has so far been known a vehicle drive apparatus as follows (see, for example, Patent Documents 1 and 2). The known vehicle drive apparatus comprises a catch tank positioned at the upper portion of a case to introduce and temporarily store therein oil (e.g., automatic transmission fluid) used for lubricating and cooling an electric motor after being drawn from the bottom portion of the case by, for example, a differential ring gear. The oil is gradually discharged from the catch tank to flow down to the operating parts and the heat-generating portions through predetermined lubricating and cooling paths formed in the vehicle drive apparatus to ensure that the operating parts are lubricated and the heat-generating portions are cooled while effectively reducing the loads of large gears and other rotation elements under operation.
Another conventional vehicle drive apparatus (see, for example, Patent Document 3) comprises a cooling system having an oil pump exemplified by a gear pump, and a heat exchanger for exchanging heat with a cooling liquid circulating path in an oil cooler and a radiator to have the oil supplied to the motor generator after the oil is cooled.
Patent Documents
Patent Document 1: Japanese Patent Publication No. 2008-195196
Patent Document 2: Japanese Patent Publication No. 2008-286247
Patent Document 3: Japanese Patent Publication No. 2006-312353